1. Field of the Invention
The invention relates to a power generating apparatus in which the speed of rotation caused by external force and transmitted from a main shaft is increased by a speed increaser to drive a generator.
2. Description of Related Art
In some conventional wind power generators, a main shaft connected to blades is rotated upon reception of wind force and the speed of rotation transmitted from the main shaft is increased by a speed increaser to drive a generator. As shown in FIG. 9, a speed increaser 202 includes a planetary gear mechanism 203, a high-speed gear mechanism 204 and an output shaft 205. The planetary gear mechanism 203 receives rotation from a main shaft 200 and increases the speed of the rotation. The high-speed gear mechanism 204 receives the rotation of which the speed has been increased by the planetary gear mechanism 203 and further increases the speed of the rotation. The output shaft 205 outputs rotary torque of the high-speed gear mechanism 204.
In the planetary gear mechanism 203, when an input shaft 203a, which is coupled to the main shaft 200 so as to be rotatable together with the main shaft 200, rotates, a planetary carrier 203b is rotated and, as a result, a sun gear 203d is rotated at an increased speed via planetary gears 203c, and the rotation of the sun gear 203d is transmitted to a low-speed shaft 204a of the high-speed gear mechanism 204. In the high-speed gear mechanism 204, when the low-speed shaft 204a rotates, an intermediate shaft 204d is rotated at an increased speed via a low-speed gear 204b and a first intermediate gear 204c, and an output shaft 205 is rotated at a further increased speed via a second intermediate gear 204e and a high-speed gear 204f. Roller bearings 206 to 211 are used as bearings by which the low-speed shaft 204a, the intermediate shaft 204d and the output shaft 205 of the speed increaser 202 are rotatably supported (see, for example, Japanese Patent Application Publication No. 2007-232186 (JP 2007-232186 A)).
The wind power generator includes a blade adjustment mechanism. When a wind force that acts on the blades becomes larger than or equal to a predetermined value due to a typhoon, gusty strong wind, or the like, the blade adjustment mechanism prevents the rotation speed of the main shaft 200 from reaching and exceeding a predetermined rotation speed by pivoting each blade about its axis to reduce the wind receiving area of each blade.
The conventional wind power generator has a problem that, in the roller bearings that support the output shaft that rotates at a high speed, smearing (phenomenon that surface seizure occurs) may occur at a rolling surface of a roller or a raceway surface of a rotary ring and, as a result, the service life of each roller bearing may decrease. In addition, if the blade adjustment mechanism malfunctions, a drive shaft of the generator may rotate at a high speed (abnormal rotation of the drive shaft may occur), and a sliding portion, such as a brush, of the generator may abnormally abrade or may break.